Acetyl CoA carboxylase (hereinafter this may be abbreviated to ACC) is an enzyme that carboxylates acetyl CoA to produce malonyl CoA, and mammals have two isozymes of ACC1 and ACC2 in their own bodies. Malonyl CoA produced by ACC may be a starting material for long-chain fatty acids or neutral fats, and in addition, it may negatively control carnitine palmitoyl transferase-1 (CPT-1) that participates in oxidative decomposition of fatty acids. Of the above isozymes, ACC1 exists in cytoplasm and is considered as a rate-limiting enzyme in biosynthesis of long-chain fatty acids, while, ACC2 exists predominantly on mitochondria and is said to participate principally in oxidation of fatty acids. Accordingly, compounds capable of inhibiting ACC1 and/or ACC2 are expected not only to inhibit synthesis of fatty acids but also to reduce accumulated fats. In fact, it is shown that, as compared with normal mice, ACC2-knocked out mice hardly get fat (see Proceedings of the National Academy of Sciences of the United States of America, 100 (18), pp. 10207-10212, 2003).
An excess of accumulated fats may cause, for example, insulin resistance, diabetes, hypertension, hyperlipemia and obesity, and it is known that a plurality of those factors, as combined, lead to an extremely higher risk of arteriosclerosis, and the symptom is referred to as a metabolic syndrome. Further, it is known that hypertriglyceridemia or obesity leads to a higher risk of, for example, pancreatitis, liver dysfunction, cancers such as breast cancer, uterine cancer, ovarian cancer, colon cancer and prostate cancer, emmeniopathy, arthritis, gout, cholecystitis, gastroesophageal reflux, pickwickian syndrome, sleep apnea syndrome. It is well known that diabetes often causes, for example, cardiac angina, heart failure, stroke, claudication, retinopathy, eyesight failure, renal failure, neuropathy, skin ulcer, infectious diseases (see The Merck Manual of Medical Information, second home edition, Merck & Co., 2003). Accordingly, ACC inhibitors are useful for the treatment and/or prevention of such disorders.
ACC exists also in plants, parasites, bacteria and fungi, and it is known that it participates in the growth of cells. For example, aryloxyphenoxypropionic acid-type herbicides represented by diclofop, and cyclohexanedione-type herbicides represented by setoxydim excert their activity by inhibiting ACC in plants (see Biochemical Society of Transaction, 22(3), p. 616 (1994)), and the aryloxyphenoxypropionic acids also exhibit a growth-inhibiting effect on parasites (see Journal of Biological Chemistry, 277 (26), pp. 23208-23215 (2002)). In addition, sorafen and moiramide B known as ACC inhibitors exhibit an antibacterial effect and an antifungal effect (see Current Genetics, 25 (2), pp. 95-100 (1994); Journal of Biological Chemistry, 279 (25), pp. 26066-26073 (2004)).
Tumor cells generally show an increased synthesis of fatty acids, and it is reported that some fatty acid synthesis inhibitors exhibit a cell growth-inhibiting effect.
Based on the above-mentioned information, ACC inhibitors are expected to be useful for the treatment and/or prevention of disorders such as hyperlipemia, fatty liver, dyslipidemia, hepatic dysfunction, obesity, diabetes, insulin resistance, metabolic syndrome, arteriosclerosis, hypertension, cardiac angina, heart failure, cardiac infarction, stroke, claudication, retinopathy, eyesight failure, renal failure, electrolyte metabolism disorder, neuropathy, skin ulcer, bulimia, pancreatitis, emmeniopathy, arthritis, gout, cholecystitis, gastroesophageal reflux, pickwickian syndrome, sleep apnea syndrome, infectious diseases, neoplasm, and also as herbicides.
Up to the present, for example, those described in a pamphlet of WO 2003/094912, WO 2003/072197, WO 2003/059886, or WO 2003/059871 are known as compounds capable of inhibiting ACC, but the compounds described in these references are totally different from the compounds of the present invention in point of their structures.
On the other hand, various compounds having the same spirochromanone skeleton as that of the compounds of the present invention are disclosed in a pamphlet of WO 95/30642, EP 431973A, WO 2004/092179 or WO 2008/065508. However, these references do neither disclose nor suggest the compounds of the invention.